In the Wideband Code Division Multiple Access (WCDMA) Release 5 (hereinafter referred to as R5) released by the 3GPP, a method for Core Network (CN) nodes jointly managing a group of Radio Network Controllers (RNCs) is described, that is, it is a conception of pool. A core network node pool is defined as that: it is unnecessary to change the area of Serving CN Node when a Mobile Station (MS) roams; one pool is served by one or multiple Serving CN Nodes jointly; and all cells managed by the RNCs belong to the same pool.
In the R5, the Network Resource Identifier (NRI) is used for identifying different Serving CN Nodes. When a mobile terminal registers in a certain pool for the first time, an RNC allocates one Serving CN Node to the mobile terminal according to a load sharing principle, and sends a registration request message of the mobile terminal to the Serving CN Node. After the registration is successful, the Serving CN Node will send an NRI corresponding to the Serving CN Node to the mobile terminal, and the mobile terminal saves the NM.
Each RNC in the pool is configured with a mapping table from the NRI to the IP address of the Serving CN Node. When the mobile terminal sends a Non-Access Stratum (NAS) message again in the pool, the mobile terminal carries the NRI in the message. The RNC searches for the IP address of the Serving CN Node from the configured mapping table according to the NRI, and forwards the NAS message from the mobile terminal to the Serving CN Node.
In the R5, in order to be compatible with the previous releases (R99 and R4), the NRI is planned as a part of Temporary Mobile Subscriber Identifier (TMSI). This limits that the number of users managed by one pool cannot exceed 2TMSI at most. Moreover, a part of the TMSI is also used as other management functions, such as a restart symbol of a Visitor Location Register (VLR) and so on, and the number of users actually managed by the pool is less than 2TMSI. This limits the extension of the pool.
Moreover, in the R5, the mapping table between the NRI and the IP address of the Serving CN Node is configured in the RNC. A configuration workload increases with the increase in the number of RNCs, the configuration workload is a product of the number of RNCs and the number of Serving CN Nodes, and this also limits the extension of the pool.
This routing method in the R5 can still adapt to the requirements of the 3rd Generation (3G) mobile communication system, because the interconnection between the RNC and the Serving CN Node actually has a certain limitation in the 3G network. However, with the constant development of Internet Protocol (IP) evolution, the all IP intercommunication can be implemented between a radio access system and a core network, and the pool can be configured to be extremely large so as to achieve the sharing of more resources, and thus, the current routing method cannot satisfy the requirements any more at this point.